Method for studying surface pollution wiping efficiency by simulating radionuclide 90Sr-90Y with rhenium element

Abstract

The invention belongs to the field of radiation environment measurement, and particularly relates to a method for studying surface pollution wiping efficiency by simulating radionuclide 90Sr-90Y with rhenium. According to the method for simulating and researching the surface pollution wiping efficiency of the radionuclide 90Sr-90Y by using the non-radioactive element rhenium element, the radioactive property of the rhenium element is combined with a radiation counting device for quantitative analysis, the radioactive pollution removal effect on different surface materials can be accurately evaluated, the method for simulating and researching the surface pollution wiping efficiency of the radionuclide 90Sr-90Y by using the non-radioactive element rhenium element is provided, the use of the radionuclide is reduced, and the cost is reduced. The method is simple and easy to operate, is friendly and safe to personnel and environment, reduces the research cost, and has applicability and operability of various materials; the radioactive contamination removal effect on different sample materials can be accurately evaluated, the method has wide applicability, and technical support can be provided for actual scientific decontamination cleaning work.

Description

Technical Field

[0001] The invention belongs to the field of radiation environment measurement, and particularly relates to a method for simulating radioactive nuclides using rhenium elements. 90 Sr- 90 Y Method to study the efficiency of wiping surface contamination. Background Art

[0002] Strontium (Sr) and yttrium (Y) are common radionuclides with long half-lives and strong radioactivity, which are extremely harmful to the environment and human body. After radiation contamination occurs, these radionuclides such as 90 Sr- 90 Y and other substances tend to adhere to the surfaces of objects made of various materials, such as metal, plastic, glass, concrete, and ceramics. In order to control the transfer of these radioactive pollutants and assess whether the radioactivity per unit area exceeds the surface contamination control level, it is necessary to conduct surface contamination measurement on the contaminated surface.

[0003] The direct measurement method is to use a surface contamination measuring instrument or monitoring instrument to measure the sum of the contamination. However, when there are interfering radiation factors such as non-radioactive liquids and sediments, as well as spatial location restrictions, direct measurement may be particularly difficult or basically impossible to implement;

[0004] Based on the above-mentioned prior art, the applicant has conducted persistent and beneficial exploration and repeated experiments, found a solution to the above-mentioned technical problems and formed the technical solution to be introduced. Summary of the invention

[0005] In order to solve the problems of the prior art, the present invention proposes a method of simulating radioactive nuclides with the non-radioactive element rhenium. 90 Sr- 90 YThe method for studying the efficiency of wiping off surface contamination can achieve the purpose of studying the efficiency of wiping off contamination on the surfaces of different objects safely, environmentally friendly and at low cost;

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for simulating radioactive nuclides using rhenium 90 Sr- 90 Y A method for studying the efficiency of surface contamination wiping includes the following steps:

[0008] 1) The experiment uses a plurality of experimental material bodies of different materials and different surface flatness. The experimental material body is a flat surface or a special-shaped material structure;

[0009] The experimental material body includes but is not limited to frosted PP board, acrylic board, silicone board, stainless steel board, aluminum board, frosted aluminum board, rubber floor, floor tile, wall tile, wooden floor, beaker, triangular flask and other flat or special-shaped materials.

[0010] 2) A certain amount of rhenium standard solution is coated on the surface of the selected experimental material, and after standing to dry, a variety of wiping material bodies are used, with and without a clamp, to wipe the contaminated parts of the surface of the experimental material body using a dry wiping material body and a uniformly wetted wiping material body.

[0011] The certain amount of rhenium standard solution described in step 2) is selected from ammonium perrhenate standard solution with a concentration of 100-500 μg / mL, preferably 200 μg / mL; when used, 0.1-1.0 mL of the solution, preferably 0.4 mL, is evenly coated on the surface of the selected experimental material and left to dry; the coating is to absorb the solution with a liquid adding gun or a graduated tube, and then evenly apply it on the object; the standing and drying is to place it in a fume hood or a ventilated and clean place for 1-3 days and dry it naturally to obtain the desired contaminated sample; the various wiping material bodies include dry filter paper, dry cotton cloth, wet filter paper, wet cotton cloth, etc., which are cut into a size similar to that of the fixture or the experimental material body; the moisture content of the uniformly wetted wiping material body is 0.008 g / cm 2 —0.020g / cm 2 , preferably 0.012 g / cm 2 .

[0012] 3) Cut off the area of ​​the bottom surface of the wiping material body that contacts the contaminated part of the experimental material, put it into a container, and soak it in a certain concentration and volume of nitric acid to extract the rhenium element. In the step 3), the nitric acid is diluted nitric acid with a concentration of 3% to 10%, preferably 5% concentration nitric acid, and the leaching time is more than 2 hours. Further, the concentration range is 4.5%-5.5%, and the volume range is 20ml-60ml. Specifically, when the wiping material is clamped with a clamp, a volume of 20mL and a concentration of 5% nitric acid are used for leaching; when the wiping material is directly pressed by hand for wiping, a volume of 60mL and a concentration of 5% nitric acid are used for leaching. During the static leaching period, the solution is shaken several times to completely dissolve the rhenium on the wiping material in the solution.

[0013] 4) After the leaching is completed, the rhenium content in the leaching solution is measured by inductively coupled plasma atomic emission spectrometry, and the rhenium wiping efficiency F of the wiping material is calculated. Re ; Step 4) Rhenium wiping efficiency F Re The calculation formula is: Rhenium wiping efficiency F Re = measured rhenium content / coated rhenium content × 100%.

[0014] 5) Verify the obtained rhenium wiping efficiency F Re The degree of simulation, verification method: a certain amount of 90 Sr- 90The Y standard solution is coated on the surface of the selected experimental material body, and after it is left to dry, the total β count rate n1 on the surface of the experimental material body before wiping is measured with a surface contamination measuring instrument; a variety of wiping material bodies are used, with and without a fixture, to wipe the contaminated parts of the surface of the experimental material with a fixed wiping method; the total β count rate n2 on the wiping material body is measured with a surface contamination measuring instrument; the total β count rate n2 on the experimental material body is calculated when the surface contamination measuring instrument is used to measure 90 Sr- 90 Y Wiping efficiency F Sr-Y ; Compare the wiping efficiency F calculated by the experimental material using the non-radioactive element rhenium Re , and using radioactive elements 90 Sr- 90 Y determines the calculated wiping efficiency F Sr-Y , verifying the use of rhenium to simulate radioactive nuclei 90 Sr- 90 Y studied the feasibility and accuracy of the surface contamination wiping efficiency method. The verification method in step 5) is to take 0.1-1.0 mL 90 Sr- 90 Y standard solution (solution system: 0.1 mol / L HCl, 30 μg / g Sr + 30 μg / g Y carrier solution, 90 Sr- 90 Y specific activity is 107Bq / g), evenly coated on the above experimental material body, placed in a fume hood or a ventilated clean place for 1-3 days, dried naturally, and the radioactive nuclides of the object were measured using a surface contamination measuring instrument 90 Sr- 90 The total beta count rate n1 of Y and the radionuclides on the wipe material 90 Sr- 90 The total count rate n2 of the upper β of Y, 90 Sr- 90 Y Wiping efficiency F Sr-Y The calculation formula is: Sr-Y =n2 / n1×100%. The surface contamination measuring instrument is CoMo 170 portable surface contamination monitor. This method uses CoMo 170 portable surface contamination monitor to measure β rays, which represents the response count of β rays of the instrument under such conditions.

[0015] Further, the wiping method with a clamp is to clamp the wiping material with a clamp, maintain constant pressure, and wipe the surface of the experimental material slowly at a uniform speed; the wiping method without a clamp is to directly press the wiping material with your hands, maintain constant pressure, and wipe the surface of the experimental material slowly at a uniform speed. For special-shaped experimental materials, the wiping method without a clamp is preferably used; the constant pressure is selected from 1 to 20N, preferably 4N pressure; the uniform speed is selected from 0.4 to 1.5cm / s, preferably 0.8cm / s.

[0016] Furthermore, the clamp body is a separate river dam-shaped structure.

[0017] Compared with the prior art, the invention has the following beneficial effects: the invention provides a method for simulating the study of radioactive nuclides using the non-radioactive element rhenium. 90 Sr- 90 The method for wiping Y surface contamination efficiently reduces the use of radioactive nuclides, is simple and easy to operate, is friendly and safe to personnel and the environment, reduces research costs, and has applicability and operability for a variety of materials; the present invention can accurately evaluate the radioactive contamination removal effect on different sample materials, has a wide range of applicability, and can provide technical support for actual scientific decontamination and cleaning work. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objectives and advantages of the present invention will become more apparent from a reading of the detailed description of non-limiting embodiments made with reference to the following accompanying drawings.

[0019] Figure 1 is a standard curve diagram of rhenium element in the present invention;

[0020] Figure 2 is a bar graph of wiping efficiency of different experimental materials in the present invention;

[0021] Figure 3 It is a wiping humidity influence curve diagram in the present invention;

[0022] Figure 4 It is a wiping speed experimental curve diagram in the present invention;

[0023] Figure 5 It is a curve diagram of the wiping stable time selection experiment in the present invention;

[0024] Figure 6 It is the rhodium background interference diagram in the present invention.

[0025] Figure 7 It is the rhenium background interference diagram in the present invention.

[0026] Figure 8 It is the indium background interference diagram in the present invention.

[0027] Fig. 9 This is a schematic diagram of the main structure of the clamp in the present invention. Figure 1 ;

[0028] Fig.10 This is a schematic diagram of the main structure of the clamp in the present invention. Figure 2 ;

[0029] Fig.11 This is a schematic diagram of the main structure of the clamp in the present invention. Figure 3 .

[0030] Among them: 100, bottom bracket; 200, trapezoidal groove; 300, pressure plate; 310, screw; 320, butterfly nut; 400, wiping material body; 210, bolt hole one; 311, bolt hole two. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below by examples, which are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0032] The indirect wiping measurement method is mostly used to measure removable contamination. However, due to the different material properties and surface roughness of the contaminated objects, the degree and distribution of radioactive nuclide contaminants adsorbed on the surface of the objects vary greatly, resulting in great uncertainty in the wiping efficiency during wiping measurement. It is impossible to better evaluate the degree of surface contamination and the decontamination effect, and it is difficult to quickly provide technical support for subsequent work decisions.

[0033] The indirect wiping measurement method depends largely on the wiping efficiency F of different object surfaces. The wiping efficiency can theoretically be experimentally determined by the "repeated wiping" method, that is, calculating the total wiping radioactivity A after multiple wiping. T , the radioactivity removed by swabbing A P With A T The wiping efficiency F is calculated by the relationship between the two. The method of calculating the wiping efficiency F by the "repeated wiping" experiment is to directly wipe the radioactive material contaminated sample with the wiping material, and then use a portable surface contamination measuring instrument or monitoring instrument to measure the radioactive activity A on the wiping material. P This method of "repeated wiping" experimental determination and calculation of wiping efficiency F has some difficulties and shortcomings in actual work, such as the use of radionuclides such as 90 Sr- 90 Y, etc., which are easy to cause environmental pollution and have certain radiation hazards to the human body during the experiment, requiring experimenters to take radiation protection; radioactive nuclides and other experimental materials are strictly controlled, difficult to purchase and expensive, and waste disposal after use is also difficult and costly; these shortcomings bring great inconvenience to the wiping efficiency F of the surface contamination of different objects by wiping method; based on this, if a method that can replace 90 Sr- 90 The method of studying the wiping efficiency F of different surface contamination by using radioactive nuclides such as Y can provide a safe, environmentally friendly, low-cost method to quickly evaluate the degree of radioactive surface contamination and decontamination effect, which is beneficial to the quality of radiation surface contamination measurement work.

[0034] Example 1: Figure 1-6 A method of using rhenium to simulate radioactive nuclides is shown. 90 Sr- 90Y A method for studying the efficiency of surface contamination wiping includes the following steps:

[0035] 1) Take 0.4 ml of ammonium perrhenate solution (concentration 200 μg / mL) and spread it evenly on the above sample material, place it in a fume hood for 1-2 days, and let it dry naturally.

[0036] 2) Use scissors to cut the filter paper or cotton cloth and other experimental materials into shapes that are convenient for wiping and sampling (matching the size of the fixture body or the size of the area to be wiped of the experimental material), and wet the filter paper or cotton cloth evenly with pure water without water seepage. The water content is about 0.012g / cm 2 .

[0037] 3) After standing for 2 minutes, place the wiping material close to the fixture base 100, flip the excess part into the trapezoidal groove 200, press the wiping material with the pressing plate 300, and fasten the base 100 and the pressing plate 300 with screws 310 to fix the wiping material; press the fixture body with the wiping material on the surface to be tested and wipe it slowly and evenly. Avoid wiping the same position repeatedly when wiping. The wiping area should be ≥ 100 cm 2 The wiping speed is 0.8 cm / s, the wiping pressure is 4 N, and the number of wiping times is 1.

[0038] 4) Remove the filter paper or cotton cloth and place it in a 100 ml plastic bottle. Use 5% nitric acid solution to make the volume 20.00 ml. Soak and extract for 2 hours. Shake the extract several times during the extraction.

[0039] 5) The inductively coupled plasma atomic emission spectrometer was turned on according to the operating instructions, and the instrument working conditions were set and the torch was ignited. The instrument working conditions were as follows: the rhenium element measurement wavelength was 221.4nm, the power was 1150W, the peristaltic pump speed was 50r / min, the auxiliary gas flow rate was 1.0L / min, the atomization gas flow rate was 0.5L / min (measured by a rotor flowmeter), the flushing time was 30s, the integration time was 30s, and the measurement was carried out in a horizontal observation mode; the preparation of the rhenium standard curve included the following steps: 5.0mL of the rhenium standard stock solution (1000μg / mL) was transferred to a 100mL volumetric flask, 5.0mL of hydrochloric acid was added, the solution was diluted to the scale with water, and the mass concentration of the solution was 50μg / mL. Then 0, 0.40, 1.00, 2.00, 4.00, and 5.00mL of the rhenium standard working solution (50μg / mL) were taken respectively, placed in a 100mL volumetric flask, 1.0mL of hydrochloric acid was added, the solution was diluted to the scale with water, and the solution was mixed. The mass concentrations of the prepared rhenium standard working solution series are 0, 0.20, 0.50, 1.00, 2.00, and 2.50 μg / mL, respectively. With the mass concentration ρ (μg / mL) of the rhenium standard solution as the horizontal coordinate and the signal intensity I as the vertical coordinate, the linear equation of the rhenium standard series is y=9964.3x+15.968, and the linear correlation coefficient is 0.9999. The content of rhenium element is determined and converted into the amount of ammonium perrhenate. The ammonium perrhenate content in the measured solution is compared with the ammonium perrhenate content sprayed on the experimental material to calculate the wiping efficiency F Re . Rhenium wiping efficiency F Re The calculation formula is: Rhenium wiping efficiency F Re = measured rhenium content / coated rhenium content × 100%.

[0040] 6) Take 0.4 ml 90 Sr- 90 Y standard solution (solution system: 0.1 mol / L HCl, 30 μg / g Sr + 30 μg / g Y carrier solution, 90 Sr- 90 Y specific activity is 107Bq / g) is evenly coated on the same experimental material, placed in a fume hood for 1-2 days, and allowed to dry naturally; the radioactive nuclides are measured using a surface contamination meter 90 Sr- 90 The total beta count rate of Y is n1; Use scissors to cut the experimental materials such as filter paper or cotton cloth into shapes that are convenient for wiping and sampling (matching the size of the fixture body or the size of the experimental material to be wiped), and use pure water to wet the filter paper or cotton cloth evenly without water seepage, the water content is about 0.012g / cm 2 After standing for 2 minutes, use a fixture to hold the wiping material, press it on the surface to be tested, and wipe it slowly and evenly. Avoid wiping the same position repeatedly. The wiping area should be ≥100cm2 ; The wiping speed is 0.8 cm / s, the wiping pressure is 4 N, and the number of wiping is 1; The radioactive nuclides are measured using a surface contamination measuring instrument 90 Sr- 90 Calculate the total β count rate n2 of Y; 90 Sr- 90 Y Wiping efficiency F Sr-Y , the calculation formula is: F Sr-Y =n2 / n1×100%. Evaluation F Re With F Sr-Y , verify the use of rhenium to simulate radionuclides 90 Sr- 90 Y studied the feasibility and accuracy of the surface contamination wiping efficiency method.

[0041] Example 2: Figure 1-6 A method of using rhenium to simulate radioactive nuclides is shown. 90 Sr- 90 Y A method for studying the efficiency of surface contamination wiping includes the following steps:

[0042] 1) Take 0.4 ml of ammonium perrhenate solution (concentration of 200 μg / ml) and spread it evenly on the above sample material, place it in a fume hood for 1-2 days, and let it dry naturally.

[0043] 2) Use scissors to cut the filter paper or cotton cloth and other experimental materials into shapes that are convenient for wiping and sampling (matching the size of the fixture body or the size of the area to be wiped of the experimental material), and wet the filter paper or cotton cloth evenly with pure water without water seepage. The water content is about 0.012g / cm 2 .

[0044] 3) After standing for 2 minutes, hold the wiping material directly with your hands, press it on the surface to be tested and wipe it slowly and evenly. Avoid wiping the same position repeatedly. The wiping area should be ≥ 100cm 2 The wiping speed is 0.8 cm / s, the wiping pressure is 4 N, and the number of wiping times is 1.

[0045] 4) Remove the filter paper or cotton cloth and place it in a 100 ml plastic bottle. Use 5% nitric acid solution to make the volume 60.00 ml. Soak and extract for 3 hours. Shake the extract several times during the extraction.

[0046] 5) The inductively coupled plasma atomic emission spectrometer was turned on according to the operating instructions, and the instrument working conditions were set and the torch was ignited. The instrument working conditions were as follows: the rhenium element measurement wavelength was 221.4nm, the power was 1150W, the peristaltic pump speed was 50r / min, the auxiliary gas flow rate was 1.0L / min, the atomization gas flow rate was 0.5L / min (measured by a rotor flowmeter), the flushing time was 30s, the integration time was 30s, and the measurement was carried out in a horizontal observation mode; the preparation of the rhenium standard curve included the following steps: 5.0mL of the rhenium standard stock solution (1000μg / mL) was transferred to a 100mL volumetric flask, 5.0mL of hydrochloric acid was added, the solution was diluted to the scale with water, and the mass concentration of the solution was 50μg / mL. Then 0, 0.40, 1.00, 2.00, 4.00, and 5.00mL of the rhenium standard working solution (50μg / mL) were taken respectively, placed in a 100mL volumetric flask, 1.0mL of hydrochloric acid was added, the solution was diluted to the scale with water, and the solution was mixed. The mass concentrations of the prepared rhenium standard working solution series are 0, 0.20, 0.50, 1.00, 2.00, and 2.50 μg / mL, respectively. With the mass concentration ρ (μg / mL) of the rhenium standard solution as the abscissa and the signal intensity I as the ordinate, the linear equation of the rhenium standard series is y=9964.3x+15.968, and the linear correlation coefficient is 0.9999. The content of rhenium element is determined and the amount of ammonium perrhenate is converted.

[0047] The wiping efficiency F is calculated by comparing the ammonium perrhenate content in the measured solution with the ammonium perrhenate content sprayed on the experimental material. Re . Rhenium wiping efficiency F Re The calculation formula is: Rhenium wiping efficiency F Re = measured rhenium content / coated rhenium content × 100%.

[0048] 6) Take 0.4 ml 90 Sr- 90 Y standard solution (solution system: 0.1 mol / L HCl, 30 μg / g Sr + 30 μg / g Y carrier solution, 90 Sr- 90 Y specific activity is 107Bq / g) is evenly coated on the same experimental material, placed in a fume hood for 1-2 days, and allowed to dry naturally; the radioactive nuclides are measured using a surface contamination meter 90 Sr- 90 The total beta count rate of Y is n1; Use scissors to cut the experimental materials such as filter paper or cotton cloth into shapes that are convenient for wiping and sampling (matching the size of the fixture body or the size of the experimental material to be wiped), and use pure water to wet the filter paper or cotton cloth evenly without water seepage, the water content is about 0.012g / cm 2After standing for 2 minutes, use a fixture to hold the wiping material, press it on the surface to be tested, and wipe it slowly and evenly. Avoid wiping the same position repeatedly. The wiping area should be ≥100cm 2 ; The wiping speed is 0.8 cm / s, the wiping pressure is 4 N, and the number of wiping is 1; The radioactive nuclides are measured using a surface contamination measuring instrument 90 Sr- 90 Calculate the total β count rate n2 of Y; 90 Sr- 90 Y Wiping efficiency F Sr-Y , the calculation formula is: F Sr-Y =n2 / n1×100%. Evaluation F Re With F Sr-Y , verify the use of rhenium to simulate radionuclides 90 Sr- 90 Y studied the feasibility and accuracy of the surface contamination wiping efficiency method.

[0049] The main body of the fixture is a separated river dam-shaped structure.

[0050] The fixture body includes a base 100, which is a rectangular plate-shaped structure; the bottom surface of the base 100 is a flat surface;

[0051] The trapezoidal groove 200 has a "︺"-shaped cross section and is opened in the middle of the upper part of the base 100. The trapezoidal groove 200 extends from one end to the other end of the base 100.

[0052] The pressing plate 300 has a "︺"-shaped cross section and is arranged to match and correspond to the trapezoidal groove 200;

[0053] The wiping material body 400 is a sheet structure, which wraps the base 100, and the two ends of the wiping material body 400 are located in the trapezoidal groove 200, the pressing plate 300 is fixed in the trapezoidal groove 200, and the bottom of the pressing plate 300 squeezes and fixes the wiping material body 400;

[0054] Specifically, the pressing plate 300 is fixedly connected to the bottom bracket 100 by means of screws 310 and butterfly nuts 320;

[0055] A bolt hole 210 is formed through the middle of the trapezoidal groove 200;

[0056] A second bolt hole 311 is formed through the middle of the pressing plate 300;

[0057] When the pressing plate 300 is installed in the trapezoidal groove 200 , the first bolt hole 210 and the second bolt hole 311 are correspondingly arranged.

[0058] The screw 310 passes through the first bolt hole 210 and the second bolt hole 311, and then the pressing plate 300 is fixed to the base 100 through the butterfly nut 320. When in use, the wiping material body 400 is closely attached to the bottom surface of the base 100, and the excess parts of the two ends of the wiping material body 400 are turned into the trapezoidal groove 200, and the two ends of the wiping material body 400 are pressed and fixed with the pressing plate 300 to prevent it from falling off during the wiping process.

[0059] The bottom of the bolt hole 210 is a conical structure, and the bottom of the screw 310 can fit into the bolt hole 210 . At this time, the bottom end surface of the screw 310 is flush with the bottom end surface of the base 100 .

[0060] The principle of conducting experiments with rhenium: The principle of selecting experimental elements is generally to avoid interference from elements in the environment. Elements with low abundance on Earth, good stability of salts, easy solubility, non-toxicity, safety and strong operability should be selected. The elements that meet the conditions are rhenium, rhodium and indium.

[0061] In comparison, the common salts of rhodium are rhodium chloride and rhodium nitrate. Rhodium chloride is easy to absorb moisture and is insoluble in water, acid, and aqua regia, but soluble in methanol and cyanide solutions; rhodium nitrate is insoluble in water, highly toxic, and flammable, and is a prohibited dangerous item. For indium, common salts include indium sulfate, which is easily soluble in water but is a moderately toxic substance. For rhenium, common salts include ammonium perrhenate, which is widely used in industry, stable at room temperature, and easily soluble in hot water. Based on the above reasons, ammonium perrhenate, a common salt of rhenium, was selected for the simulation experiment. In terms of instrument testing: indium has a low signal value; rhodium has a large background interference; and rhenium has a large signal intensity, high sensitivity, and no interference, which meets the selection principle of tracer elements. Table 1 shows the signal intensity of 0.5μg / mL standard solution of indium, rhenium, and rhodium measured by inductively coupled plasma atomic emission spectrometer, and calculates their respective signal-to-background ratios.

[0062]

[0063] Table 1

[0064] at the same time Figure 6 , 7 8 are the background interference images of rhodium (Rh), rhenium (Re), and indium (In), Figure 6 , Figure 7 , Figure 8 It can be seen that Figure 6 The background interference of rhodium is large, and the spectral lines are interfered; Figure 8 The background interference of indium is small but the signal intensity is low and the sensitivity is low; Figure 7 Rhenium has small background interference and high signal intensity, which means that the element's determination sensitivity is also high, so rhenium is the best experimental element.

[0065] Experimental verification of the wiping efficiency of rhenium and radioactive elements strontium-90 and yttrium-90:

[0066] To illustrate the use of non-radioactive elements to simulate radionuclides 90 Sr- 90 Y studied the feasibility and accuracy of surface contamination wiping efficiency. The conventional method of wiping efficiency of radioactive elements strontium-90 and yttrium-90 was used. That is, a certain amount of radioactive elements strontium-90 and yttrium-90 were directly coated on the experimental materials. The radionuclides on the experimental materials were measured using the CoMo 170 portable surface contamination monitor. 90 Sr- 90 The total beta count rate n1 of Y and the radionuclides on the wipe material 90 Sr- 90 The total count rate n2 of the upper beta of Y, 90 Sr- 90 Y Wiping efficiency F Sr-Y The calculation formula is: Sr-Y =n2 / n1×100%. Table 2 shows the wiping efficiency of rhenium and 90 Sr- 90 Y Wiping efficiency F Sr-Y Comparison chart.

[0067]

[0068] Table 2

[0069] Wipe wetness options:

[0070] The humidity of the wiping material is an important factor affecting the efficiency of wiping radioactive surface contamination. When the humidity of the wiping material is low, its ability to adsorb radioactive contaminants may be limited. The dry wiping material does not have sufficient contact with the contaminated surface, making it difficult to effectively capture and adsorb contaminant particles, resulting in reduced wiping efficiency. This may cause some contaminants to remain on the surface and cannot be completely removed. As the humidity of the wiping material increases, its wet surface is able to better fit the contaminated surface, enhancing its affinity and adsorption for contaminants. The presence of water molecules helps to dissolve and loosen some tightly attached contaminants, thereby improving the ability of the wiping material to capture contaminants and, in turn, improving wiping efficiency. The experiment was conducted on cotton cloth with moisture levels of 0, 1.0, 2.0, and 3.0, such as Figure 3 As shown, the results show that the data is stable between 2.0-3.0 for wipe moisture.

[0071] Selection of stabilization time:

[0072] The wiping stabilization time refers to the time to keep the water evenly dispersed after the cotton cloth is soaked, in order to ensure the uniform humidity of the cotton cloth. It is very important to choose the appropriate wiping stabilization time. If the stabilization time is too short, the water in the cotton cloth may not be evenly dispersed, resulting in low wiping efficiency, incomplete collection of pollutants, and underestimation of the degree of contamination, which affects the accuracy of the detection. On the contrary, if the humidity stabilization time of the cotton cloth is too long, it may cause the water in the wiping material to evaporate and change its adsorption properties; it may also increase operation time and cost and reduce detection efficiency. This experiment tested the humidity stabilization time of the cotton cloth at 0, 1.0, 2.0, 3.0, 4.0, and 5.0 minutes, respectively. Figure 5 As shown, from Figure 5 It can be seen that the humidity stabilization time of cotton cloth is 2-3min.

[0073] Wiping speed selection:

[0074] In the wiping operation of radioactive surface contamination detection, a faster wiping speed may not give the wiping material enough time to fully contact the contaminated surface and adsorb the contaminants, resulting in reduced wiping efficiency, failure to effectively remove radioactive contaminants, and affecting the accuracy of the test results. Too slow a wiping speed may increase operation time and reduce work efficiency. Moreover, wiping slowly in the same area for a long time may change the physical or chemical state of the contaminants due to factors such as frictional heat generation, and may even cause the spread of contaminants. This experiment tested four speeds of 0.4cm / s, 0.6cm / s, 0.8cm / s, and 1.5cm / s, and the results are shown in the figure. Figure 4 ,from Figure 4 It can be seen that the result of fast wiping is unstable and the wiping efficiency is low. The experiment chooses a wiping speed of 0.8 cm / s.

[0075] Selection of wiping pressure and wiping times:

[0076] Since both parameters affect the wiping efficiency, experiments were conducted on them. When the number of wiping times was fixed at 1, the optimal humidity wiping pressure was selected to vary between 1-5N. The results showed that the wiping results were most stable when the wiping efficiency was 4N, and the RSD of the wiping efficiency of various plates was less than 5%. When the wiping pressure was fixed at 4N, the number of wiping times varied between 1-5 times. For most plates with flat and smooth surfaces, after 1 wiping, the results of 2-5 wiping times were basically zero. For plates with corrugated surfaces, such as bean-grain aluminum plates, multiple wiping is required to meet the requirements.

[0077] Wiping method selection:

[0078] Fix the wiping pressure and humidity, use a clamp and hands to wipe the contaminated plate respectively. In actual work, we can choose the appropriate wiping method according to the shape of the material. For example, the wiping efficiency and effect of the clamp is better for flat materials, and the wiping effect of hands is better for special-shaped materials.

[0079] Extraction experiment:

[0080] In the present method, the leaching experiment selects 5% nitric acid solution to soak the filter paper or cotton cloth, and the soaking time is not less than 2 hours. During the leaching period, the leaching solution is shaken several times to improve the leaching efficiency. The leaching efficiency is experimentally determined. The filter paper and cotton cloth are quantitatively coated with rhenium standard solution, and 0.1, 0.2, 0.3, and 0.4 mL of 80.00 μg / mL rhenium solution are coated respectively. After stabilization for 10 minutes, 20.00 mL of 5% nitric acid solution is used for leaching. After the required leaching time is reached, the rhenium element content is determined by inductively coupled plasma atomic emission spectrometer. The leaching efficiency is calculated, and the results are shown in Table 3. Table 3 is the experimental data of 5% nitric acid leaching efficiency. From the data in the table, it can be seen that the leaching efficiency of the four specifications of pollutants after contaminating the filter paper and cotton cloth is 100.02%-101.63%. The experiment shows that 5% nitric acid solution is effective in removing pollutants of different concentrations. This method uses 5% nitric acid solution for leaching.

[0081]

[0082] Table 3

[0083] Wiping material selection experiment:

[0084] Different wiping materials have a significant impact on wiping efficiency. Filter paper has a strong adsorption capacity for tiny particles due to its fine fiber structure, but it may not be efficient enough when wiping a large area. Cotton cloth has good water absorption and can remove liquid pollutants well, but it has limited removal effect on some sticky pollutants. Seven filter paper and cotton cloth wiping experiments were conducted on four types of plates, and the results are shown in Table 4. Table 4 shows the data of using filter paper and cotton cloth to wipe the four types of plates.

[0085]

[0086] Table 4

[0087] As can be seen from Table 4, the average wiping efficiency of bean-grain aluminum plate using filter paper and cotton cloth is 15.60% and 31.89% respectively, and the RSD is 11.77% and 3.39% respectively; the average wiping efficiency of plastic plate using filter paper and cotton cloth is 35.09% and 51.75% respectively, and the RSD is 17.77% and 1.98% respectively; the average wiping efficiency of stainless steel plate using filter paper and cotton cloth is 70.82% and 81.49% respectively, and the RSD is 7.47% and 3.24% respectively; the average wiping efficiency of soft silicone plate using filter paper and cotton cloth is 92.94% and 94.07% respectively, and the RSD is 3.10% and 1.06% respectively. The wiping efficiency of the four plates using cotton cloth is higher than that using filter paper, and the wiping efficiency is stable. The wiping efficiency results of soft silicone plate using filter paper and cotton cloth are not much different, and the wiping efficiency is stable. In practical applications, if you are looking for a higher and more stable wiping efficiency, choose cotton cloth to wipe the rough and uneven surface of the plate, and choose filter paper or cotton cloth for the smooth and flat surface of the plate. Cotton cloth has better wiping efficiency.

[0088] In the description of the present invention, it is necessary to understand that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicate orientations or positional relationships of devices or equipment during normal use, rather than indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention in this regard.

[0089] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that this is only for illustration and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A method of simulating radioactive nuclides using rhenium 90 Sr- 90 Y is a method for studying the efficiency of wiping surface contamination, characterized in that, The steps include: 1) The experiment uses a plurality of experimental material bodies with different materials and different surface flatness; the experimental material body is a flat surface or a special-shaped material structure; 2) Coat a certain amount of rhenium standard solution on the surface of the selected experimental material, let it stand and dry, and then use a variety of wiping material bodies, with and without a clamp, to wipe the contaminated parts of the surface of the experimental material body using a dry wiping material body and a uniformly wetted wiping material body; 3) Cut off the area on the bottom of the wiping material body that contacts the contaminated part of the experimental material, put it in a container, and soak it in a certain volume of nitric acid with a certain concentration to extract the rhenium element. The nitric acid is diluted nitric acid with a concentration of 3% to 10%. When 5% nitric acid is used, the leaching time is more than 2 hours; 4) After the leaching is completed, the rhenium content in the leaching solution is measured by inductively coupled plasma atomic emission spectrometry, and the rhenium wiping efficiency F of the wiping material is calculated. Re ; Step 4) Rhenium wiping efficiency F Re The calculation formula is: Rhenium wiping efficiency F Re = measured rhenium content / coated rhenium content × 100%; 5) Verify the obtained rhenium wiping efficiency F Re The degree of simulation, verification method: a certain amount of 90 Sr- 90 The Y standard solution is coated on the surface of the selected experimental material body, and after it is left to dry, the total β count rate n1 on the surface of the experimental material body before wiping is measured with a surface contamination measuring instrument; a variety of wiping material bodies are used, with and without a fixture, to wipe the contaminated parts of the surface of the experimental material with a fixed wiping method; the total β count rate n2 on the wiping material body is measured with a surface contamination measuring instrument; the total β count rate n2 on the experimental material body is calculated when the surface contamination measuring instrument is used to measure 90 Sr- 90 Y Wiping efficiency F Sr-Y ; Compare the wiping efficiency F calculated by the experimental material using the non-radioactive element rhenium Re , and using radioactive elements 90 Sr- 90 Y determines the calculated wiping efficiency F Sr-Y , verifying the use of rhenium to simulate radioactive nuclei 90 Sr- 90 Y studied the feasibility and accuracy of the surface contamination wiping efficiency method; The wiping method with a clamp is to clamp the wiping material with a clamp, maintain constant pressure, and wipe the surface of the experimental material slowly at a uniform speed; the wiping method without a clamp is to directly press the wiping material with the hand, maintain constant pressure, and wipe the surface of the experimental material slowly at a uniform speed. For special-shaped experimental materials, the wiping method without a clamp is preferably used; the constant pressure is selected from 1 to 20N, and the uniform speed is selected from 0.4 to 1.5cm / s.

2. The method of simulating radioactive nuclides with rhenium according to claim 1. 90 Sr- 90 Y is a method for studying the efficiency of wiping surface contamination, characterized in that, The verification method in step 5) is to take 0.1 to 1.0 mL 90 Sr- 90 Y standard solution is evenly coated on the body of the above experimental material, placed in a fume hood or a ventilated and clean place for 1-3 days, dried naturally, and the radioactive nuclides of the object are measured using a surface contamination measuring instrument 90 Sr- 90 The total beta count rate n1 of Y and the radionuclides on the wipe material 90 Sr- 90 The total count rate n2 of the upper beta of Y, 90 Sr- 90 Y Wiping efficiency F Sr-Y The calculation formula is: Sr-Y =n2 / n1×100%.

3. The method of simulating radioactive nuclides with rhenium according to claim 2 90 Sr- 90 Y is a method for studying the efficiency of wiping surface contamination, characterized in that, The certain amount of rhenium standard solution described in step 2) is selected from ammonium perrhenate standard solution with a concentration of 100-500 μg / mL; when in use, take 0.1-1.0 mL of the solution, evenly apply it on the surface of the selected experimental material and let it stand to dry; the coating is to use a liquid adding gun or a graduated tube to absorb the solution and then evenly apply it on the object; standing to dry is to place it in a fume hood or a clean and ventilated place for 1-3 days and dry it naturally to obtain the desired contaminated sample.

4. The method of simulating radioactive nuclides with rhenium according to claim 3. 90 Sr- 90 Y is a method for studying the efficiency of wiping surface contamination, characterized in that, The wiping material body comprises dry filter paper, dry cotton cloth, wet filter paper and wet cotton cloth; the wiping material body is uniformly wetted so that its moisture content is 0.008 g / cm 2 —0.020g / cm 2 .

5. The method of simulating radioactive nuclides with rhenium according to claim 4. 90 Sr- 90 Y is a method for studying the efficiency of wiping surface contamination, characterized in that, When the wiping material is clamped with a clamp, a volume of 20 mL and a concentration of 5% nitric acid is used for immersion; when the wiping material is directly pressed by hand for wiping, a volume of 60 mL and a concentration of 5% nitric acid is used for immersion. During the static immersion period, the solution is shaken several times to allow the rhenium on the wiping material to be completely dissolved in the solution.

6. The method of simulating radioactive nuclides with rhenium according to claim 5. 90 Sr- 90 Y is a method for studying the efficiency of wiping surface contamination, characterized in that, The clamp body is a separated river dam-shaped structure.

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